Nor did it occur when he won a role on an iconic series that has lasted nine seasons and won four Emmy Awards.

And no, it wasn't when he was called back for a second episode on a popular sitcom, either.

Rather, for the 20-year-old Groveland native, that moment came while he was riding in a carpet-cleaning truck.

The handsome, young actor leans forward and fidgets in his seat as he recounts the emotion of the day.

"So here I am in this van that says 'Carpet Cops' on the side with my buddy," said Fuller, who now lives in Los Angeles. "The sun was going down, it was beautiful out, and a Coldplay song was on the radio."

He was on his way to help his friend rip up a rug.

"I just said out loud, 'This — Los Angeles — is where I am supposed to be. It's going to be hard, but I just have this feeling. This is a new chapter for me. This is where I have to be,'" he recalls.

Two years after leaving home to pursue a career in acting, Fuller has begun to make a name for himself in Hollywood.

He has made guest appearances on ABC's hit medical drama "Grey's Anatomy," the ABC sitcom "Suburgatory" and the MTV comedy/drama "Awkward."

"I have a tradition that every time I get a part, I open a bottle of Champagne and save the cork," said Fuller, a 2011 Pentucket High graduate. "I write the name and date of the show and put the cork on my mantel. That's how I celebrate. I have three so far."

The acting bug bit Fuller when he was a sixth-grader.

"That year, I auditioned for the school play, and to my surprise, I got the lead role," he said. "I loved it. I felt very at home in front of the audience, very happy performing. The rush of the applause was such a nice high. After that, I knew it was something I wanted to do."

His proud grandmother helped kick-start his career.

"My nana went to an agency in New Hampshire one day," Fuller said. "She said, 'I have this grandson and I want to show him to you.' They ended up bringing me in for an interview. I auditioned for them, and they wanted to sign me right there. They then connected me with an agency in LA."

Through middle school and high school, Fuller, also a talented football player and track athlete, dedicated himself to his passion, taking trips to New York and California for auditions and other opportunities.

"I would go for trips up to a month long to do what they call 'pilot season,'" he said. "I would go for the experience and to test my luck. I also received some really valuable training."

He found success in commercials, appearing in ads for Hood milk and Nerf toy guns, and in a comic piece for the popular humor website Funny or Die. He also appeared in seven independent short films, including a starring role in the 2010 release "Taking a Shot at Love," which won him best new actor at the Atlantic City Cinefest film festival.

After finishing high school, Fuller made the decision to move to Los Angeles.

"I think it was actually after the move had already happened that I began to get nervous," he said. "I had been going out to LA with my parents, and it had been the plan. I never had any second thoughts. Then, after living there for a while, I realized, 'I am thousands of miles away from my family in a big city where people get hurt. Wouldn't it be easier to just go to a four-year school?' But I knew what I wanted to do."

After a grueling series of auditions, Fuller hit his first success when he read for "Awkward."

"Now, 99 percent of the auditions you go on don't work out. I had gotten the audition for this two-line part about two days before I actually had to audition," he said. "I was with my acting coach, and he said, 'I have a weird feeling about this. I think you're going to get this.'

"So I walk into an office in downtown Hollywood. The part was for the devil, so I wore a red shirt and thought to myself, 'How would the devil sit? How devilish can I make that guy?' So I read, and they told me it was the best reading that had seen all day. That totally threw me off."

A day later, Fuller officially received his first national TV job, as Devil on the episode "Are You There God? It's Me, Jenna." The show aired July 19, 2012.

"I had a party the night it aired," he said. "It was my first role, and I wanted to share it with everyone. But once it came on, it was just too weird to watch. After that, I decided I wasn't going to have another party. After that, it was just business."

Not long after, Fuller experienced a bit of a premonition.

"I live near the Warner Bros. lot, and one day, I was walking past it," he remembers. "I stopped and said over and over in my head, 'One day, I'll work in the Warner Bros. lot.' Two weeks later, I was working on the lot."

That part was as football jock Derek in the "Suburgatory" episode "Chinese Chicken."

"'Awkward' was great," he said. "But 'Suburgatory' was my first time on a full set. I walked onto the lot and I had my own trailer. I just thought to myself, 'Oh, my God! I am really here.' It was just a one-line role, but that is my foot in the door."

The latest success came on "Grey's Anatomy," a ratings juggernaut entering its 10th season. He was cast as Cash Keller in the episode "Sleeping Monster," where his character requires surgery after severing a finger.

On the day of his audition, he also benefited from some accidental method acting.

"My character was supposed to be mad, so I went into the audition thinking I was going to be angry," he said. "I also happened to really be upset about something that day, so it had a level of realism. About a week and a half passed, and I hadn't heard from them, so I assumed nothing was going to happen.

"Then I ended up getting a callback and I read for the director, producer and all the writers. And they laughed; I was just so thrilled. Two days later, they called me and I got the part. It was extremely professional working on such a famous show."

Now, with a growing résumé and a budding career, Fuller expresses more confidence about his place in the acting world.

"When I first got 'Awkward,' I wondered if I had just gotten lucky," he said. "Maybe that would be my claim to fame. But this year, I started to notice that it wasn't just the parts I did get, it was also the parts I didn't get. Casting directors would say, 'He was great, but just wasn't right for this part because he wasn't old enough or young enough. But he was awesome.'

"I feel more comfortable with where I am in my life and where I am as a person. I look back at three years ago, or even six months ago, and shake my head at what I was thinking then. I feel like my confidence has grown, and I feel like, maybe, I can do this."

His maturity and calm demeanor make his mother, Heidi Fuller, believe her son can be successful.

"Being an actor is a very, very hard journey," she said. "The pre-eminent quality in Sam that makes us comfortable letting him do this is that he is very resilient. You have to develop a thick skin and temper your emotions in both failure and success."

Watching him perform is an unusual experience, she said.

"It is a very strange and surreal feeling seeing your son on television," she said. "It is easy to support Sam because he works so hard."